Fix rotated virtual display size detection

The physical size of the virtual display does not change when the
display is rotated, although the reported display size does.

Refs #6772 comment <https://github.com/Genymobile/scrcpy/pull/6772#pullrequestreview-4238019023>
PR #6772 <https://github.com/Genymobile/scrcpy/pull/6772>